When stocks are attractive, you buy them. Sure, they can go lower. I’ve bought stocks at $12 that went to $2, but then they later went to $30.

Happiness， like unhappiness， is a proactive choice.

可持续性不再是选择，而是我们对后代的责任。

When I see someone wasting a glass of water, I think of those who don't have water on Earth.

I want to disappear into the universe, become part of it.

数学的语言是普遍的，超越了文化和语言的障碍。